Recently, in mobile communication systems, such as those for mobile telephones, as one example of faster data communication specifications, Long Term Evolution (LTE) has been under investigation. LTE standardization is progressing under the 3rd Generation Partnership Project (3GPP), a standardization organization for third generation mobile communication systems, and is a communication scheme expanding third generation mobile telephone (3G) communication performed under wideband code division multiple access (W-CDMA) schemes (see, for example, “3GPP TR 25.913 V7.3.0(2006-03))”, 3rd Generation Partnership Project, p. 1-18).
Under LTE, to reduce energy consumption, mobile stations perform intermittent reception (discontinuous receiving for power saving (DRX)) of signals from a base station not only while waiting for communication but also during communication. During intermittent reception, a given mobile station receives a scheduling channel periodically and checks for transmissions addressed thereto. Further, to maintain synchronization of the uplink, the given mobile station performs uplink transmission to the base station periodically (discontinuous transmission (DTX)).
Further, among network configuration methods realizing internet protocol (IP) communication, a method has been proposed under which various types of wireless base station communication areas have hierarchical relations. A method has been further proposed where, when a wireless terminal equipped with various types of wireless devices has one or more of the wireless devices set to a hibernation mode, route registry packets that include an identifier of the base station having the largest communication area among wireless base stations counterpart to the wireless devices, are transmitted to a core router (see, for example, Japanese Laid-Open Patent Publication No. 2004-304280 ([claim 2], [claim 5])).